The present invention relates generally to optical and other instruments requiring light sources, and more specifically to an optical fiber apparatus that replaces an incandescent light bulb with an auxiliary light source which may include a laser.
Optical and other instruments frequently use incandescent light bulbs as a source of light. For example, many ophthalmic instruments, such as a retinascope, incorporate a slit lamp to project a thin bar-shaped beam of light upon an eye. Typical slit lamps use a small incandescent bulb as the light source. Such incandescent bulbs are limited in the amount of light they can produce by the temperature to which their filaments can be heated before melting or otherwise greatly reducing their useful operating life. These bulb filaments typically operate at a compromise temperature of about 2,860.degree. K., producing a light spectrum with a visible peak in the red, but not strong enough in intensity for many ophthalmic investigations preferably done with red light. The desired bar-shape of the light beam is generally formed by projecting the light through a mechanical slit, which reduces the available total amount of light.
While present slit lamps are successfully used for many eye examinations, their light intensity usually is wanting for examining eyes made opaque from cataracts, the use of cholonergic glaucoma medication, or from other causes.
U.S. Pat. No. 3,068,745 to Peck describes a slit lamp for projecting a beam of light with very well defined edges. Peck optically connects a fiber optic bundle to an intense source of white light. Each individual fiber in the bundle is tapered from a wide end at the light source to a thin end at optics in front of an output light slit. An input light slit in front of the wide ends of the fibers shapes the light beam before it enters the optical fiber bundle. The progressive taper of the individual fibers produces a smaller bar-shaped light beam at the output end of the fiber bundle, but with much more sharply defined edges. While Peck's use of an optical fiber bundle allows the use of a brighter lamp than in typical slit lamps, much of the available light is lost by the light blocking effect of the input and output light slits. It is thus seen that there is a need for a more efficient solution which yields highly intense light for use as a source in ophthalmic and other instruments.
It is, therefore, a principal object of the present invention to provide light with a higher intensity than yielded by conventional straight-forward optical instrument light sources.
It is another object of the present invention to furnish light of high intensity in a versatile retinascope whereby convenient, one-handed operation, including focusing and rotation of the slit projection from the light source, still is maintained.